Proportional electromagnet and electromagnetic valve

Abstract

The invention discloses a proportional electromagnet and an electromagnetic valve. The technical problems that an existing proportional electromagnet is large in size, high in assembly precision requirement and poor in armature position detection precision are mainly solved. The magnetic shell is provided with a cylindrical cavity along the central axis; the iron core is relatively fixed in the cylindrical cavity and is provided with an armature moving cavity along the central axis; the winding is wound between the magnetic shell and the iron core; the armature is movably embedded in the armature moving cavity; the core cap is arranged at one end of the iron core and is used for sealing the armature moving cavity; the magnetic sensor is embedded in the core cap and is used for detecting the position of the armature; and the thickness direction of the magnetic sensor is the same as the movement direction of the armature. The proportion electromagnet has the advantages of being small in size, wide in application range, high in armature action position control precision, easy to assemble, high in yield and the like.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic control technology, and in particular to a proportional electromagnet and a solenoid valve. Background Art

[0002] An electromagnet is a device that can generate a magnetic field. It consists of a number of coils wound around an iron core. When current flows through the coils, a magnetic field is generated, which in turn forms magnetic lines of force around the iron core, attracting or repelling ferrous materials. The iron material is generally an armature embedded in the iron core, so that the armature is affected by the magnetic lines of force and moves accordingly to achieve the effects of operating and pulling mechanical devices. Among them, the iron core is generally made of highly permeable and easily magnetized materials, such as soft iron, electrical steel, etc.; the coil is wound with insulated wires, usually copper wire or aluminum wire. A proportional electromagnet is a type of electromagnet that can generate a mechanical quantity (force or torque and displacement) that is proportional to the size of the input signal (current).

[0003] Proportional solenoids and hydraulic valves can be used to remotely control valves in various hydraulic and pneumatic systems. When current passes through the coil winding of the electromagnet, the electromagnetic suction force overcomes the spring resistance of the reset spring inside the solenoid valve, prompting the push rod of the valve body to move, thereby opening the valve. After the coil winding is powered off, the valve body push rod is reset under the action of the reset spring and the valve is closed. Proportional solenoids can continuously control the pressure, direction and flow of the hydraulic system by controlling the position of the hydraulic valve core. However, with the continuous improvement of the control accuracy and reliability requirements of the hydraulic system, there is a need to accurately detect the action position of the armature, and then determine whether the armature is in place through armature position detection.

[0004] The existing proportional electromagnet armature position detection method known to the inventor is to detect the armature position by setting an LVDT linear position sensor. However, in the process of realizing the technical solution in the embodiment of the present application, the inventor of the present application found that when using the LVDT linear displacement sensor to detect the armature position, the armature needs to be axially lengthened along the armature axis so that the armature is within the detection range of the LVDT linear displacement sensor, which will increase the axial length and volume of the proportional electromagnet; in addition, when using the LVDT linear position sensor to detect the armature position, its assembly accuracy requirements are high, and the detection accuracy is limited, resulting in a large detection error.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] In view of at least one of the above technical problems, the present disclosure provides a proportional solenoid and a solenoid valve, aiming to solve the technical problems that the existing proportional solenoids are large in size, have high assembly precision requirements, and have poor armature position detection accuracy.

[0007] According to one aspect of the present disclosure, there is provided a proportional electromagnet, which includes a magnetic shell provided with a cylindrical cavity along a central axis, an iron core relatively fixed in the cylindrical cavity and provided with an armature movable cavity along the central axis, a winding wound between the magnetic shell and the iron core, an armature movably embedded in the armature movable cavity, a core cap provided at one end of the iron core for closing the armature movable cavity, and a magnetic sensor embedded in the core cap for detecting the position of the armature; the thickness direction of the magnetic sensor is in the same direction as the movement direction of the armature.

[0008] In some embodiments of the present disclosure, the magnetic sensor is correspondingly installed on the circuit board.

[0009] In some embodiments of the present disclosure, the circuit board is an annular structure, and the magnetic sensor is a TMR sensor; at least one of the magnetic sensors is electrically connected to the annular circuit board.

[0010] In some embodiments of the present disclosure, two of the magnetic sensors are electrically connected to the annular circuit board, and the two magnetic sensors are symmetrically arranged on both sides of the annular circuit board with respect to the center of the annular circuit board.

[0011] In some embodiments of the present disclosure, the magnetic sensor includes four wiring terminals, and a magnetoresistance effect element whose resistance changes with the external magnetic field is connected in series between corresponding adjacent wiring terminals; the circuit board is electrically connected with a signal output wire that is conductive corresponding to the wiring terminals; the resistance of the magnetoresistance effect element changes with the change of the magnetic field along the direction of movement of the armature.

[0012] In some embodiments of the present disclosure, the magnetic sensor is a Hall sensor.

[0013] In some embodiments of the present disclosure, a push rod hole for movably embedding a manual push rod is axially opened at the center position of the core cap.

[0014] In some embodiments of the present disclosure, assuming that the radius of the armature is R, the distance between the magnetic sensor and the central axis of the armature is ΔX, the maximum distance between the magnetic sensor and the end face of the armature is ΔZ, and the stroke of the armature is L, then ΔX / R≤0.75, ΔX≥2, ΔZ>L, ΔZ<2R+L.

[0015] In some embodiments of the present disclosure, the iron core includes a fixed iron core body, a guide sleeve fixed to one end of the fixed iron core body through a magnetic isolation sleeve for forming the armature movable cavity, and a magnetic isolation plate arranged at the end surface of the fixed iron core body for contacting the armature; the fixed iron core body and the guide sleeve are magnetic material parts; the magnetic isolation sleeve and the magnetic isolation plate are non-magnetic material parts.

[0016] According to another aspect of the present disclosure, a solenoid valve is provided, which includes the above-mentioned proportional solenoid.

[0017] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: The magnetic sensor embedded in the core cap can accurately detect the position of the armature of the proportional electromagnet, thereby avoiding the problem of increasing the volume of the proportional electromagnet due to the axial extension of the armature in the prior art, and realizing the miniaturization of the proportional electromagnet; and based on the boundary conditions identified by long-term practical research experience, the relative installation position of the magnetic sensor in the core cap is reasonably limited, ensuring a wider signal output range of the magnetic sensor, and can effectively improve the detection accuracy and reliability of the proportional electromagnet for the armature position; in addition, keeping the thickness direction of the magnetic sensor consistent with the movement direction of the armature can accurately detect the armature position while avoiding the adverse effects of installation errors on measurement accuracy, reducing assembly accuracy and improving the yield rate; thereby reducing the selection complexity of the magnetic sensor, avoiding the additional setting of a magnetic field, and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of a proportional electromagnet in one embodiment of the present application.

[0019] Figure 2 FIG. 1 is a partial structural diagram of a magnetic sensor in an embodiment of the present application.

[0020] Figure 3 FIG. 1 is a partial structural diagram of a magnetic sensor in another embodiment of the present application.

[0021] Figure 4 This is a test curve diagram of the magnetic field strength of the proportional electromagnet when ΔX=4mm in one embodiment of the present application.

[0022] Figure 5 This is a test curve diagram of the magnetic field strength of the proportional electromagnet when ΔX=8mm in one embodiment of the present application.

[0023] Figure 6 This is an experimental curve diagram of the sensor signal output range under different values ​​of ΔX and ΔZ in one embodiment of the present application.

[0024] In the above figures, 1 is a magnetic housing, 21 is a fixed core body, 22 is a magnetic isolation sleeve, 23 is a guide sleeve, 3 is a winding, 31 is a skeleton, 4 is an armature, 5 is a core cap, 6 is a magnetic sensor, 61 is a circuit board, and 7 is a manual push rod. DETAILED DESCRIPTION

[0025] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", "horizontal", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on this application. The "connection" and "coupling" involved in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0026] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0027] In order to solve the technical problems in the prior art of using LVDT linear position sensor to detect the armature position of proportional electromagnet, such as poor detection accuracy, high assembly accuracy requirement of sensor at proportional electromagnet and increase of volume of proportional electromagnet, this example discloses a proportional electromagnet, see Figure 1 , which includes a magnetic shell 1. In this embodiment, the magnetic shell 1 is a soft magnetic material with a certain wall thickness, and its outer edge profile is cylindrical. A cylindrical cavity is opened along its central axis, that is, the magnetic shell 1 is a cylindrical shell structure as a whole. An iron core is fixedly embedded in the cylindrical cavity of the magnetic shell 1, and a winding 3 is provided between the iron core and the magnetic shell. For details, see Figure 1 In this example, the winding 3 is wound with a metal wire such as a copper wire, and the winding 2 is enclosed outside the iron core by a magnetic shell 1. The winding 3 is provided with two winding terminals and extends from the magnetic shell 1 for connecting to a power source, thereby connecting the winding 3 to the power source. When the winding 3 is connected to the power source, the winding 3 is energized and current flows through it, thereby generating a magnetic field at the winding 3. Since the magnetic shell 1 is made of a magnetic material, it can constrain the magnetic field at the winding 3, reduce leakage magnetic field, and avoid the magnetic field from spreading outward as much as possible. In this embodiment, considering that the winding 3 is wound with a thin and soft metal wire, in order to avoid the winding from being formed and deformed by external interference, see Figure 1 In this example, the middle winding 3 is wound on the frame 31.

[0028] In this example, an armature is embedded in the core along the central axis of the core, see Figure 1In this example, the iron core includes a fixed iron core body 21, a magnetic isolation sleeve 22, a guide sleeve 23 and a magnetic isolation sheet ( Figure 1 (not shown). Specifically, the fixed core body 21 is fixed to one side of the cylindrical cavity of the magnetic shell 1, and the end of the fixed core body 21 located in the cylindrical cavity of the magnetic shell 1 is coaxially connected to the guide sleeve 23 through the magnetic isolation sleeve 22, wherein the outer edge diameter of the guide sleeve 23 matches the outer edge diameter of the fixed core body 21, and an armature movable cavity is formed in the core through the guide sleeve 23, which is used to embed the armature 4 in the armature movable cavity along the axial direction of the core. Among them, the inner edge diameter of the armature movable cavity matches the outer edge diameter of the armature 4, ensuring that the armature 4 moves smoothly in the armature movable cavity while avoiding the armature from shaking in the moving axis when moving, and at the same time ensuring that the length of the armature movable cavity is greater than the designed movement length of the armature. Therefore, the fixed core body 21 can play a role in concentrating the magnetic field to increase the magnetic flux and magnetic field strength. When the winding 3 is energized to generate a magnetic field, the armature 4 is magnetized accordingly, thereby generating an electromagnetic attraction between the fixed core body 21, causing the armature to move, realizing the action of the proportional electromagnet, and then adjusting the magnitude of the current flowing through the winding 3 to adjust the magnetic field strength, so as to achieve the purpose of adjusting the electromagnetic force on the armature 4, thereby realizing the proportional position control of the armature. In this embodiment, a magnetic isolation plate is provided at the end face of the fixed core body 21 for contacting the armature 4, thereby avoiding the problem of excessive electromagnetic force caused by direct contact between the armature 4 and the fixed core body 21. Among them, the fixed core body 21 and the guide sleeve 23 are both magnetic material parts, and the magnetic isolation sleeve 22 and the magnetic isolation plate are both non-magnetic material parts.

[0029] See also Figure 1 In order to prevent the armature 4 from falling off from the armature movable cavity, a core cap 5 for sealing the armature movable cavity is provided at the end of the iron core. A magnetic sensor 6 for detecting the position of the armature 4 is embedded in the core cap 5. In this embodiment, the magnetic sensor is specifically a TMR sensor. The thickness direction of the magnetic sensor 6 is in the same direction as the movement direction of the armature 4, thereby making the sensor signal output variation introduced by the assembly position error of the sensor smaller, effectively reducing the assembly difficulty and improving the yield rate. In order to facilitate the installation and signal output of the magnetic sensor, at least one magnetic sensor is correspondingly installed at the PCB circuit board. Specifically in this embodiment, see Figure 2The circuit board 61 is an annular structural member, and two magnetic sensors 6 are symmetrically arranged on both sides of the annular circuit board 61 about the center of the circuit board 61. Correspondingly, an annular groove matching the contour of the annular circuit board of the magnetic sensor is opened at the end side of the core cap 5 for assembling and embedding the magnetic sensor and the circuit board. Among them, in this example, the Z direction is perpendicular to the circuit board, that is, the thickness direction of the magnetic sensor. By arranging the thickness direction of the magnetic sensor in the same direction as the movement direction of the armature, the magnetic sensor can detect the magnetic field in the Z direction. At the same time, in this example, the magnetic sensors 62 are symmetrically arranged on both sides of the circuit board, which can effectively eliminate the measurement error caused by the assembly deviation of the magnetic sensor tilted along the X direction or the Y direction when the magnetic sensor is assembled in the groove at the core cap 5. In some other embodiments, refer to Figure 3 The circuit board 61 is a disc-shaped structure, and a magnetic sensor 6 is electrically connected to the surface of the circuit board 61. A cylindrical groove with a certain depth is opened at the core cap 5 along the movement direction of the armature to place and assemble the magnetic sensor 6, so that the thickness direction of the magnetic sensor 6 is in the same direction as the movement direction of the armature to realize the magnetic field detection in the Z direction. In some other embodiments, the magnetic sensor is a Hall sensor.

[0030] In this embodiment, the magnetic sensor 6 includes four terminals, each of which corresponds to four pins on the periphery of the magnetic sensor, and magnetoresistance effect elements are connected in series between adjacent terminals, and the resistance of the magnetoresistance effect element can change with the change of the external magnetic field; in this embodiment, since the thickness direction of the magnetic sensor is in the same direction as the movement direction of the armature, the resistance of each magnetoresistance effect element in the magnetic sensor can change with the change of the magnetic field along the movement direction of the armature. In addition, in this example, the circuit board is also provided with output wires electrically connected to each terminal. Specifically, the magnetoresistance effect element includes a free layer, an intermediate layer and a fixed layer, wherein the magnetization direction of the fixed layer does not change with the external magnetic field, while the magnetization direction of the free layer changes with the external magnetic field. When the armature position changes, the magnetic field around the magnetic sensor changes, and then the angle between the magnetization directions of the fixed layer and the free layer changes, and the resistance of the magnetoresistance effect element also changes with the change of the angle. Thus, the magnetic sensor generates a change in sensor output due to the change in the resistance of the corresponding magnetoresistance effect element, and the change in the armature position and the specific position are judged.

[0031] See also Figure 1 In order to facilitate the manual control of the armature when the electromagnet is powered off, a push rod hole is opened along the central axis of the core cap 5 in this example, and a manual push rod 7 is movably embedded in the push rod hole, thereby pushing the end of the manual push rod 7 to contact the armature, thereby pushing the armature to move. In addition, in this embodiment, see Figure 1, assuming that the radius of the armature 4 is R, the distance between the magnetic sensor 6 and the central axis of the armature is ΔX, the maximum distance between the magnetic sensor 6 and the end face of the armature is ΔZ, and the stroke of the armature 4 is L. The inventor has found based on long-term practical research that when ΔX / R≤0.75, the intensity of the signal output can be ensured, and ΔX≥2 can ensure that the push rod has a certain installation space, and make ΔZ>L to avoid collision between the armature and the sensor; in addition, ΔZ<2R+L is set to limit the overall length of the proportional electromagnet to ensure the miniaturization of the electromagnet.

[0032] In this embodiment, the magnetic field strength of the electromagnet was verified under the values ​​of ΔX=4mm and ΔZ=8.51+4mm, and ΔX=8mm and ΔZ=8.51+4mm, respectively. The results are shown in Figure 4 and Figure 5 , where the horizontal axis Stroke represents the distance between the armature and the fixed core body, in mm. Figure 4 and Figure 5 It can be seen that with the movement of the armature, the axial magnetic field component in the electromagnet, that is, the magnetic field component Bz along the direction of armature movement, changes greatly, while the magnetic sensor with the thickness direction in the same direction as the axial direction of armature movement can effectively detect the magnetic field component Bz; in addition, when ΔX changes from 4mm to 8mm, the change of the magnetic field component Bz is very small, which reflects that the technical solution of this application can avoid the adverse effect of sensor installation error on sensor measurement accuracy. In addition, this example also conducted verification tests on the sensor signal output range for different combinations of ΔX and ΔZ values, and the results are shown in Figure 6 ; It can be seen from the figure that when the changes of ΔX and ΔZ are within the range of ±1mm, the change of the sensor signal output is very small. It can be seen that the use of magnetic sensors has lower assembly tolerance requirements, which can effectively reduce the difficulty of assembly, improve the yield rate, and reduce production costs.

[0033] In addition, this example also discloses a solenoid valve including the above-mentioned proportional solenoid, which includes a hydraulic valve and the above-mentioned proportional solenoid. The hydraulic valve is coaxially fixedly connected to the proportional solenoid, and the valve core in the hydraulic valve is coaxially transmission connected to the armature of the proportional solenoid. When the winding is energized, the armature movement can be controlled accordingly, thereby driving the hydraulic valve core to move, thereby achieving different degrees of conduction of the solenoid valve, and the magnetic sensor at the core cap of the proportional solenoid accurately detects the position of the armature, thereby determining the position of the hydraulic valve core and achieving precise control of the solenoid valve.

[0034] Although some preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0035] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variations to the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A proportional electromagnet, characterized in that: It includes a magnetic shell with a cylindrical cavity along the central axis, an iron core relatively fixed in the cylindrical cavity and provided with an armature movable cavity along the central axis, a winding wound between the magnetic shell and the iron core, an armature movably embedded in the armature movable cavity, a core cap provided at one end of the iron core for closing the armature movable cavity, and a magnetic sensor embedded in the core cap for detecting the position of the armature; the thickness direction of the magnetic sensor is in the same direction as the movement direction of the armature.

2. The proportional electromagnet according to claim 1, characterized in that: The magnetic sensor is correspondingly arranged on the circuit board.

3. The proportional electromagnet according to claim 2, characterized in that: The circuit board is an annular structure, and the magnetic sensor is a TMR sensor; at least one magnetic sensor is electrically connected to the annular circuit board.

4. The proportional electromagnet according to claim 3, characterized in that: The annular circuit board is electrically connected to two magnetic sensors, and the two magnetic sensors are symmetrically arranged on both sides of the annular circuit board with respect to the center of the annular circuit board.

5. The proportional electromagnet according to claim 2, characterized in that: The magnetic sensor includes four terminals, and a magnetoresistance effect element whose resistance changes with the external magnetic field is connected in series between corresponding adjacent terminals; the circuit board is electrically connected with a signal output wire that is conductive corresponding to the terminals; the resistance of the magnetoresistance effect element changes with the change of the magnetic field along the direction of movement of the armature.

6. The proportional electromagnet according to claim 1, characterized in that: The magnetic sensor is a Hall sensor.

7. The proportional electromagnet according to claim 1, characterized in that: A push rod hole for movably embedding a manual push rod is axially provided at the center of the core cap.

8. The proportional electromagnet according to claim 7, characterized in that The radius of the armature is R, the distance between the magnetic sensor and the central axis of the armature is ΔX, the maximum distance between the magnetic sensor and the end face of the armature is ΔZ, and the stroke of the armature is L, then ΔX / R≤0.75, ΔX≥2, ΔZ>L, ΔZ<2R+L.

9. The proportional electromagnet according to claim 1, characterized in that: The iron core includes a fixed iron core body, a guide sleeve fixed to one end of the fixed iron core body through a magnetic isolation sleeve for forming the armature movable cavity, and a magnetic isolation plate arranged on the fixed iron core body for contacting the end surface of the armature; the fixed iron core body and the guide sleeve are magnetic material parts; the magnetic isolation sleeve and the magnetic isolation plate are non-magnetic material parts.

10. A solenoid valve, characterized in that: The invention comprises the proportional electromagnet as claimed in claim 1.

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